For improvement of traffic safety and comfort in automobile driving, items of vehicle-mounted equipment are increasing in number. To be concrete, it can be mentioned that air conditioning and audio equipment have become standard and car navigation systems have come into widespread use. It is expected, in the near future, that installation on board of such equipment related to car communications as represented by telelmatics will become prevalent.
In line with such multifunctionalization of vehicle mounted equipment, there are disclosures of on-vehicle input equipment published, for example, in Japanese Patent Unexamined Publication Nos. 2003-54290 and H10-333764. An example of the same is shown in FIG. 8. Switch devices 8, 9 are each constructed of rotary dial knob (hereinafter called “knob”) 12 incorporating a rotary encoder therein and display 13 disposed in the center thereof. Although it is not shown, switch devices 8, 9 each has a built-in tact switch.
When an item of vehicle-mounted equipment is to be controlled by one of switch devices 8, 9, knob 12 is pressed and thereby a tact switch is depressed so that functions of the switch devices are switched from one to another. FIG. 8 shows a state in which the function of air conditioner's temperature setting is switch-selected. When the function is switched over, display 13 displays the currently established function and the current set value. In FIG. 8, there are displayed “TEMP” representing the function of temperature setting and “25.0” indicating the set temperature. It is arranged such that the input function causes the temperature to be changed by having knob 12 rotated in a direction. In other words, by turning knob 12, the temperature can be changed at will.
In like manner, by pressing knob 12 to select a function of sound level control, the sound level can be changed at will by using same knob 12. Thus, by using the described switch assembly, multiple functions of on-vehicle equipment can be controlled with a smaller number of switch devices.
Meanwhile, there is a need for making switch controlling of multiple functions while a driver is driving an automobile vehicle. Under such conditions, it is not necessarily so, for the sake of traffic safety, that the operator can control the functions by visually recognizing the switches. Therefore, there is a need for input devices enabling the driver to have control command signals input therethrough safely and certainly even without looking at the switches.
In the above mentioned switch assembly, the number of switches are not so large that the cases are rare in which the driver is puzzled or makes mistakes in manipulating them. However, knob 12 is completely circular in shape and the driver makes inputting of the driving direction by means of a rotary encoder. Since the rotary encoder freely rotates 360°, it is impossible for the driver to know what the currently set value is only by touching the switch. This means that the driver is required to look at display 13. Although such an advantage can be obtained that the number of switches is reduced, the driver is unable to make the control with his or her eyes turned away from the switches. Thus, it is impossible for the driver to manipulate the switch safely and certainly only with the touch of a hand on the switch.